linux - arm组装指令中的“.inst”是什么意思

Question

内核版本：4.14.199

crash 中的 spin_lock 汇编指令是

crash_arm64> dis _raw_spin_lock -x
0xffffff8008c41e90 <_raw_spin_lock>:    stp     x29, x30, [sp,#-32]!
0xffffff8008c41e94 <_raw_spin_lock+0x4>:        str     x19, [sp,#16]
0xffffff8008c41e98 <_raw_spin_lock+0x8>:        mov     x29, sp
0xffffff8008c41e9c <_raw_spin_lock+0xc>:        mov     x19, x0
0xffffff8008c41ea0 <_raw_spin_lock+0x10>:       nop
0xffffff8008c41ea4 <_raw_spin_lock+0x14>:       mov     w0, #0x1                        // #1
0xffffff8008c41ea8 <_raw_spin_lock+0x18>:       bl      0xffffff80080f399c <preempt_count_add>
0xffffff8008c41eac <_raw_spin_lock+0x1c>:       mov     w10, #0x10000                   // #65536
0xffffff8008c41eb0 <_raw_spin_lock+0x20>:       .inst   0xb8aa0268 ; undefined
0xffffff8008c41eb4 <_raw_spin_lock+0x24>:       nop
0xffffff8008c41eb8 <_raw_spin_lock+0x28>:       nop
0xffffff8008c41ebc <_raw_spin_lock+0x2c>:       nop
0xffffff8008c41ec0 <_raw_spin_lock+0x30>:       eor     w9, w8, w8, ror #16
0xffffff8008c41ec4 <_raw_spin_lock+0x34>:       cbz     w9, 0xffffff8008c41edc <_raw_spin_lock+0x4c>
0xffffff8008c41ec8 <_raw_spin_lock+0x38>:       sevl
0xffffff8008c41ecc <_raw_spin_lock+0x3c>:       wfe
0xffffff8008c41ed0 <_raw_spin_lock+0x40>:       ldaxrh  w10, [x19]
0xffffff8008c41ed4 <_raw_spin_lock+0x44>:       eor     w9, w10, w8, lsr #16
0xffffff8008c41ed8 <_raw_spin_lock+0x48>:       cbnz    w9, 0xffffff8008c41ecc <_raw_spin_lock+0x3c>
0xffffff8008c41edc <_raw_spin_lock+0x4c>:       ldr     x19, [sp,#16]
0xffffff8008c41ee0 <_raw_spin_lock+0x50>:       ldp     x29, x30, [sp],#32
0xffffff8008c41ee4 <_raw_spin_lock+0x54>:       ret

.inst指令的含义是什么？

0xffffff8008c41eb0 <_raw_spin_lock+0x20>:       .inst   0xb8aa0268 ; undefined

我在arch/arm64/include/asm/spinlock.h.

static inline void arch_spin_lock(arch_spinlock_t *lock)
{
        unsigned int tmp;
        arch_spinlock_t lockval, newval;

        asm volatile(
        /* Atomically increment the next ticket. */
        ARM64_LSE_ATOMIC_INSN(
        /* LL/SC */
"       prfm    pstl1strm, %3\n"
"1:     ldaxr   %w0, %3\n"
"       add     %w1, %w0, %w5\n"
"       stxr    %w2, %w1, %3\n"
"       cbnz    %w2, 1b\n",
        /* LSE atomics */
"       mov     %w2, %w5\n"
"       ldadda  %w2, %w0, %3\n"
        __nops(3)
        )

        /* Did we get the lock? */
"       eor     %w1, %w0, %w0, ror #16\n"
"       cbz     %w1, 3f\n"
        /*
         * No: spin on the owner. Send a local event to avoid missing an
         * unlock before the exclusive load.
         */
"       sevl\n"
"2:     wfe\n"
"       ldaxrh  %w2, %4\n"
"       eor     %w1, %w2, %w0, lsr #16\n"
"       cbnz    %w1, 2b\n"
        /* We got the lock. Critical section starts here. */
"3:"
        : "=&r" (lockval), "=&r" (newval), "=&r" (tmp), "+Q" (*lock)
        : "Q" (lock->owner), "I" (1 << TICKET_SHIFT)
        : "memory");
}

在我看来，.inst 0xb8aa0268应该对应于ldadda %w2, %w0, %3\n".

为什么显示的崩溃与源代码不同？

标签： linuxlinux-kernellocking